This invention relates to a device for the separation of platelet rich plasma from whole blood. The invention represents an adaptation to the platelet transfusion service of the process and a device disclosed in the co-pending application by Maxim D. Persidsky entitled Process and Device for Centrifugal Separation of Platelets.
According to this device the separation of dissimilar solid particles, such as platelets and other blood cells, is effected by holding red and white blood cells with the aid of centrifugal force at a steady state equilibrium in a chamber, preferably of a conical shape, while displacing platelet rich plasma (PRP) with an equivalent volume of normal saline which is filtering through the suspension of blood cells in the direction generally against the centrifugal force. The liquid medium enters the conical chamber at its vertex which is oriented away from the center of rotation, thereby being at the centrifugal outer end of the chamber, while PRP exits the chamber through its base, which is the centrifugal inner end of the chamber. The liquid flow is generated by means of a piston pump in response to centrifugal force. The apparatus is designed as an insert to be used in a centrifuge swinging bucket, and consists of a cylinder and a piston, the latter incorporating both the conical separation chamber at its lower end and the PRP receiving chamber at its upper end. There is a needle valve in the piston controlling the flow rate of the medium flowing from the cylinder through the passageway leading to the conical chamber's centrifugal outer end. To prevent an immediate discharge of blood cells from the conical chamber by the flow of saline at the start of centrifugation, a control means is provided for holding movement of the piston into the cylinder until a maximum centrifugal force is applied. The control means comprises an o-ring on the piston received in a groove in the wall of the cylinder. This provision allows one to clear blood cells from the centripetal end of the chamber by sedimenting cells at a low centrifugal speed applied for one minute after which centrifugal speed is raised to a required higher value at which the o-ring snaps from the groove and the piston begins to force medium from the cylinder into the conical chamber.